Field of the Invention
The present invention relates to projection apparatuses and methods for controlling the projection apparatuses, and a computer-readable storage medium, and relates in particular to techniques for projecting a stereoscopic image using a plurality of projectors.
Description of the Related Art
Stereoscopic images, which are images three-dimensionally perceived by an observer, have been widely used mainly in the fields of entertainment and education. Many stereoscopic images utilize spatial displacement between a left image viewed by the left eye of the observer and a right image viewed by the right eye thereof, i.e., a parallax. The observer three-dimensionally perceives an image by fusing, in the brain, the left image and the right image having the parallax. The stereoscopic effect perceived by the observer depends on the parallax. That is to say, the parallax need only be adjusted in order to change the stereoscopic effect to be perceived by the observer. Hereinafter, the stereoscopic effect perceived by the observer will be referred to as a “stereoscopic degree” only in the case where confusion will not occur.
Furthermore, the size of stereoscopic images has been increasing for the purpose of enhancing the impressiveness of the images and making the images more appealing. As a system for increasing the size of images, a multi-projection system has been widely used that combines a plurality of projection-type image display apparatuses to display one image. This is because a large screen can be easily configured by combining the plurality of projection-type image display apparatuses. Note that the multi-projection system is applicable not only to projection of stereoscopic images but also to projection of two-dimensional images.
The multi-projection system projects images such that a portion of a projected image overlaps a portion of an adjacent projected image in order to make the boundary between these projected images adjacent to each other less noticeable. However, even with projection apparatuses of the same model, a difference in tint, luminance, or the position or the shape of a displayed object may possibly exist between projected images due to variation and change over time of constituent elements (apparatuses and devices serving as components) constituting the projection apparatuses. If a difference exists between the projected images, a plurality of images exist in an overlapping region where a plurality of projected images overlap each other, the image quality deteriorates, and the observer feels a sense of incongruity. Accordingly, the difference between the projection apparatuses needs to be reduced such that the tint, the luminance, and the position and the shape of a displayed object are consistent between projected images with which the overlapping region is projected.
Furthermore, in the case of a multi-projection system that projects stereoscopic images, the stereoscopic degree must be consistent between the overlapping region and the other region. For example, it is assumed that one display target (e.g., projected image) exists spanning the overlapping region and the other region. If the stereoscopic degree is inconsistent between the overlapping region and the other region, the display target discontinuously changes at the boundary between the overlapping region and the other region. If the display target discontinuously changes even though this display target is a single object, the possibility arises that the stereoscopic image quality thereof deteriorates, the observer gets confused, and it becomes difficult to view the display target as a stereoscopic image, or the observer feels more fatigued due to viewing the stereoscopic image. For this reason, in the multi-projection system that projects stereoscopic images, it is necessary to adjust, in addition to the aforementioned item, the parallax, i.e., displacement between the left image and the right image and reduce a difference in the stereoscopic degree in order to prevent a difference from occurring in the stereoscopic degree between the overlapping region and the other region.
In this regard, a technique for reducing such a difference between images in the multi-projection system has been proposed. Japanese Patent Laid-Open No. 2010-085562 describes a technique by which projection apparatuses project different reference patterns and cameras of the projection apparatuses photograph these reference patterns. In this configuration, the position of a point of measurement is calculated to adjust a display position based on the photographed reference patterns. With this configuration, the influence of a difference in the position or the shape of a displayed object can be reduced.
Japanese Patent Laid-Open No. 2011-211693 describes a technique by which a reference pattern is projected using invisible light and this reference pattern is photographed by a camera of a projection apparatus. In this configuration, the position of a point of measurement is calculated to adjust a display position based on the photographed reference pattern. With this configuration, since the reference pattern is projected using invisible light, the adjustment can be performed even while actual images are being projected.
However, with the configuration in Japanese Patent Laid-Open No. 2010-085562, the display position is adjusted independently from actual image projection, and therefore displacement in the images cannot be adjusted while the actual images are being projected. Accordingly, this configuration cannot deal with a difference in the stereoscopic degree that occurs while the actual images are being projected.
Moreover, since this configuration does not include a configuration for measuring a difference in the stereoscopic degree, the stereoscopic degree cannot be adjusted.